The invention relates to a rotating electrical machine having an internally located rotor and an externally located stator that is assembled from an outer stator ring and an inner stator ring. The invention also relates to a method for manufacturing such a machine.
In machines with a rotor and a stator, configurations have become known in which the stator is built up from an outer stator ring and an inner stator ring. These two rings are in turn assembled from flat structural elements. All of these have the same shape. They are placed one upon the other and then pressed. Because the edge profiles of the flat structural elements are uniform for all the layers, there is a through gap that causes a substantial magnetic reluctance. The outer and inner stator rings are permanently connected together by a bonding agent. The gap is filled with a bonding agent that represents a substantial hindrance to the magnetic flux and for the removal of heat. Pollutants contained in the bonding agent also damage the environment.
The invention is therefore based on the object of presenting a machine, of the type mentioned at the beginning, in which it is possible to dispense with a bonding agent for connecting the outer stator ring to the inner stator ring. The invention is also based on the object of presenting a process by which such a machine can be manufactured.
It is accordingly an object of the invention to provide a rotating electrical machine and a process for manufacturing it that overcome the disadvantages of the prior art devices and methods of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a rotatable electrical machine. The machine contains an internally located rotor, and an externally located stator surrounding the rotor. The stator has an outer stator ring and an inner stator ring disposed in the outer stator ring. The outer stator ring and the inner stator ring are each wound from at least one strip and are permanently connected together mechanically.
In accordance with an added feature of the invention, the outer stator ring is shrunk onto the inner stator ring, the inner stator ring is shrunk into the outer stator ring, or the outer stator ring is shrunk on and the inner stator ring is shrunk into the outer stator ring.
In accordance with an additional feature of the invention, the strip forming the outer stator ring has a longitudinal axis, a longitudinal edge and wedge-shaped notches formed therein along the longitudinal edge. The notches have an inner end, longitudinal axes directed at right angles to the longitudinal axis of the strip, and an opening angle dimensioned just sufficiently large for the wedge-shaped notches to just close after a winding process. The strip further has a hole with a specifiable cross section at the inner end of each of the wedge-shaped notches.
In accordance with another feature of the invention, the longitudinal edge of the strip is provided with a concave curvature between each two of the wedge-shaped notches. The strip additionally has a further longitudinal edge provided with a convex curvature that is disposed opposite of the longitudinal edge. A distance between each of the two wedge-shaped notches has a length L=Di*sin (xcfx80/(nsxc2x11/m)), where Di is an inner diameter of the outer stator ring, nsxc2x11/m is a number of sections between the wedge-shaped notches which are necessary for winding a layer onto a mandrel, and an overlap of the sections from layer to layer is determined by m.
In accordance with another added feature of the invention, the strip is wound to form the outer stator ring such that the outer stator ring has an inner region bounded by the concave curvature of the longitudinal edge.
In accordance with another additional feature of the invention, the strip forming the inner stator ring has a width, a longitudinal axis and teeth. The teeth have longitudinal axes directed at right angles to the longitudinal axis of the strip, and the teeth have a length matched to the width of the strip.
In accordance with yet another feature of the invention, the teeth have a width, free first ends with flanks, and wedge-shaped recesses formed on each of the flanks. The strip forming the inner stator has webs each with a center region. The teeth have second ends connected to each other by the webs and each set of two of the teeth each directly following one another are connected together in each case by adjacent ones of the webs. The webs further have a length matched to the width of the teeth, and the webs have first and second longitudinal edges with a recess formed in at least one of the longitudinal edges in the center region.
With the foregoing and other objects in view there is further provided, in accordance with the invention, a process for manufacturing a rotatable electrical machine. The process includes the steps of providing an internally located rotor; and providing an externally located stator surrounding the rotor. The stator has an outer stator ring and an inner stator ring each wound from at least one strip and are subsequently permanently connected together mechanically.
In accordance with an added feature of the invention, there is the further step of shrinking the outer stator ring onto the inner stator ring, shrinking the inner stator ring into the outer stator ring, or shrinking the outer stator ring on the inner stator ring and shrinking the inner stator ring into the outer stator ring.
In accordance with an additional feature of the invention, there is the step of manufacturing the outer stator ring from the strip by a winding process. The strip has a longitudinal axis, a longitudinal edge and wedge-shaped notches formed along the longitudinal edge. The notches have an inner end, longitudinal axes directed at right angles to the longitudinal axis of the strip, and an opening angle dimensioned such that the wedge-shaped notches just close after the winding process. The strip further has holes with a specifiable cross section and one of the holes is formed at the inner end of each of the wedge-shaped notches.
In accordance with another feature of the invention, there is the step of forming each section of the strip disposed between two of the wedge-shaped notches with a concave curvature along the longitudinal edge. The section with a convex curvature is formed along a further longitudinal edge disposed opposite the longitudinal edge. And the strip of the outer stator ring is formed such that a distance between each two of the wedge-shaped notches has a length L=Di*sin (xcfx80/(nsxc2x11/m)), where Di is an inner diameter of the outer stator ring, nsxc2x11/m is a number of sections between the wedge-shaped notches which are necessary for winding a layer on a mandrel for forming the outer stator ring, and an overlap of the sections from layer to layer is determined by m.
In accordance with yet another feature of the invention, there is the step of winding the strip forming the outer stator ring such that each of the notches of each layer is overlapped by a completely closed piece of the strip in order to avoid air gaps.
In accordance with another added feature of the invention, there is the step of winding the strip forming the outer stator ring on a mandrel having an outer diameter selected to be equal to or slightly smaller than an inner diameter of the outer stator ring. The strip forming the outer stator ring is wound onto the mandrel such that the longitudinal edge with the wedge-shaped notches bears on the mandrel.
In accordance with another additional feature of the invention, there is the step of forming the strip for the inner stator ring with teeth. The teeth have longitudinal axes directed at right angles to a longitudinal axis of the strip forming the inner stator ring and a length of the teeth is matched to a width of the strip forming the inner stator ring. The strip is wound for forming the inner stator ring.
In accordance with an added feature of the invention, there is the step of forming the teeth, in a region of a first free end, with a wedge-shaped recess on flanks of the teeth. And forming the strip for the inner stator ring with webs disposed between and connecting second ends of adjacent ones of the teeth. A length of the webs is matched with a width of the teeth and the webs have in a central region a recess on at least one of two longitudinal edges of each the webs.
In accordance with another feature of the invention, there are the steps of forming the inner stator ring by winding the strip onto a mandrel such that the webs bear on the mandrel; and subsequently disposing an electrical winding in each case in a space formed between two stacks of the teeth.
In accordance with a concomitant feature of the invention, there is the step of forming a further outer stator ring from at least one further strip and using the further outer stator ring as a part of the rotor.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a rotating electrical machine and a process for manufacturing it, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.